Something weird is going on then, I happily Save As pdf and
dwg/dxf all the time and it always shows the hidden lines in the
views.

How much data is in your drawings? When you fully expand the
feature manager for the drawing are the little hour glasses on the
views gone before you try to Save As your drawing. The hour glass
represents that SW is still working to fully resolve the views in
the drawings.

Also a bit more detail on what version and SP of SW and also some
computer specs will help us help you.

I had issues with saving in different formats (s-drawings and
PDF's) then I discovered that the users were not setting the
drawing views to High Quality. If the views are still in Draft
Quality or not finish building then the quality of the translation
will be poor.

The SAVE AS a PDF file works great! That is not the problem. The problem is that when I use the "convert to PDF" task in EPDM lines are dropped or added to the PDF file that were not vivible in the source drawing.